biostudies-literatureCoonrod EMNIGMS NIH HHS462-8https://www.ebi.ac.uk/biostudies/studies/S-EPMC4086684biostudies-literatureUnknown27(4)Studies of homotypic vacuole-vacuole fusion in the yeast Saccharomyces cerevisiae have been instrumental in determining the cellular machinery required for eukaryotic membrane fusion and have implicated the vacuolar H(+)-ATPase (V-ATPase). The V-ATPase is a multisubunit, rotary proton pump whose precise role in homotypic fusion is controversial. Models formulated from in vitro studies suggest that it is the proteolipid proton-translocating pore of the V-ATPase that functions in fusion, with further studies in worms, flies, zebrafish, and mice appearing to support this model. We present two in vivo assays and use a mutant V-ATPase subunit to establish that it is the H(+)-translocation/vacuole acidification function, rather than the physical presence of the V-ATPase, that promotes homotypic vacuole fusion in yeast. Furthermore, we show that acidification of the yeast vacuole in the absence of the V-ATPase rescues vacuole-fusion defects. Our results clarify the in vivo requirements of acidification for membrane fusion.Developmental cellHomotypic vacuole fusion in yeast requires organelle acidification and not the V-ATPase membrane domain.PMC4086684GM38006R37 GM032448GM32448F32 GM083572GM835722R01 GM032448R01 GM038006Bowers KStirrat LBryant NJStevens THGraham LACarr TMCoonrod EMCarpp LNfalseHomotypic vacuole fusion in yeast requires organelle acidification and not the V-ATPase membrane domain.Studies of homotypic vacuole-vacuole fusion in the yeast Saccharomyces cerevisiae have been instrumental in determining the cellular machinery required for eukaryotic membrane fusion and have implicated the vacuolar H(+)-ATPase (V-ATPase). The V-ATPase is a multisubunit, rotary proton pump whose precise role in homotypic fusion is controversial. Models formulated from in vitro studies suggest that it is the proteolipid proton-translocating pore of the V-ATPase that functions in fusion, with further studies in worms, flies, zebrafish, and mice appearing to support this model. We present two in vivo assays and use a mutant V-ATPase subunit to establish that it is the H(+)-translocation/vacuole acidification function, rather than the physical presence of the V-ATPase, that promotes homotypic vacuole fusion in yeast. Furthermore, we show that acidification of the yeast vacuole in the absence of the V-ATPase rescues vacuole-fusion defects. Our results clarify the in vivo requirements of acidification for membrane fusion.2013-01-01T00:00:00Z2013 Nov2020-10-29T11:29:27Z2019-03-27T01:31:42ZS-EPMC40866842428682710.1016/j.devcel.2013.10.014